Nowadays, electronic products, equipped with cameras in the market, mostly focus on wide viewing angle and short object distance. If a person wants to capture an image of a distanced small object, optical designs of these cameras cannot meet such requirements. A camera with a telescopic capacity generally uses a multi-group zoom lens design and is equipped with spherical lenses. Such a structure leads the camera to occupy a large volume, which is not beneficial for small-size designs. Accordingly, existing optical systems cannot meet the average customers' requirements in pursuing functional and convenient photographing experiences.